1. Field of the Invention
The disclosure generally relates to a communication device, and more particularly, relates to a communication device comprising a dual-antenna system with high isolation characteristics.
2. Description of the Related Art
When mobile technology transmission rates increase, more and more antennas are required to be designed into mobile devices in order to increase data transmission amounts. Accordingly, a general antenna system (e.g., a dual-antenna WWAN (Wireless Wide Area Network) system which has functions of dual-SIM (Subscriber Identity Module), dual-standby, and dual-talk) is preferably disposed at one end of a handheld device (e.g., the bottom of a mobile phone) so that the bandwidth and the SAR (Specific Absorption Rate) of the antenna system can easily meet requirements. However, it is difficult to improve the isolation of the antenna system for WWAN high bands (e.g., a GSM1800/1900 band). The main reason is for this, is that mutual coupling between antennas increases since surface currents on a ground plane of a mobile device are easily excited along an antenna system operating at high bands. Thus, maintaining a high amount of isolation and reducing mutual coupling and interference between antennas in a limited space of a mobile device are critical challenges for antenna designers.